1. Field of the Invention
This invention relates to compressors and particularly to devices adapted to prevent leakage of the air or gas being compressed by submerging or surrounding the compressor mechanism or some portion thereof in a fluid.
2. Description of the Prior Art
In the construction of sliding vane rotary type compressors, the clearance between the end of the rotor and the end covers of the compressor housing is critical to the functioning of the device. If this clearance is too large, gas compressed in the pocket formed by cylinder wall of the compressor housing, the rotor, adjacent sliding vanes and the end covers of the compressor housing will leak from one pocket to the adjacent pocket of lower pressure, substantially reducing the efficiency and output of the compressor. If the tolerance between the end of the rotor and the end covers of the housing is too small, there will be an interference of the parts which can result in damage to the machinery as well as reduced performance. In view of these facts, it is not unusual to find that maching tolerances measured in the ten thousandths of an inch (0.0001) are required in order to properly position the end covers to the cylindrical section of the compressor housing.
Because the tolerances are so important, it is not possible to use any gasket type sealing means between the end covers of the compressor housing and the cylindrical section of the housing to prevent leakage from the compressor to the atmosphere. The interposing of any .Iadd.gasket .Iaddend.between the end covers and the cylindrical section would place a component of variable dimension in the chain of elements whose overall dimension must be held to within the above mentioned ten thousandths of an inch.
Therefore, to provide sealing between the front cover of the compressor and the compressor housing, the prior art had to use an O-ring type seal disposed between the circumferential surface of the front cover and the inner wall of the cylindrical section of the compressor housing. This type of construction is shown in FIG. 2 of U.S. Pat. No. 3,385,513 issued May 28, 1968 to C. R. Kilgore where an O-ring 20 is disposed between the outer wall 11 of the housing and the front cover 13a.
The problems with this type of sealing arrangement are the relative inefficient seal provided by an O-ring seal assembly as compared to a gasket sealing assembly, and the rapid deterioration of the O-ring sealing member as compared to a gasket sealing member for this type of application. The latter factor results from hardening, cracking and permanent deformation of the O-ring due to the heat, air and oil to which the O-ring is exposed in a typical compressor application. Additionally, it is often necessary to remove the covers of the compressor for periodic servicing of the vanes and bearings within the compressor, and therefore the covers must be slid out of engagement from the cylindrical section of the housing thereby rubbing and scuffing the O-ring seal along the inner wall of the housing.
To overcome the problems of the prior art the applicant has provided a new, improved construction for a rotary compressor in which leakage from the compressor to atmosphere through the interface between the cylindrical section of the compressor housing and the covers of the compressor housing is prevented by a gasket type sealing means without in any way effecting the relative position of the front cover to the compressor rotor.
A new construction accomplishes this end by placing the compressor housing substantially in the tank which receives the compressor discharge and seals the front cover of the compressor with a gasket-type seal to the wall of the receiver tank. By this construction, the interfaces between the cylindrical section of the compressor housing and the covers of the housing are located in an enclosed area sealed from the atmosphere. A gasket-type seal can be used to seal the front cover of the compressor to the tank, without effecting the performance of the compressor in any way, to prevent leakage from the tank to atmosphere. If any leakage does occur it would be "inward" leakage from the discharge tank back into the compressor housing. This inward leakage is much less serious then a comparable conventional leakage from the compressor housing to atmosphere since the inward leakage does not have as great an effect as conventional leakage on compressor efficiency and output.
Accordingly, it is an object of the present invention to provide a compressor assembly in which no special intervening sealing medium is required between the covers of the compressor housing and the cylindrical section of the compressor housing to effectively seal the interfaces between these elements from the atmosphere.
Another object of the present invention is to provide a compressor assembly in which the compressor is substantially located within the tank which receives the compressor discharge.
Yet, another object of the present invention is to provide a compressor assembly in which the sealing means to prevent leakage from the compressor housing to the atmosphere can be effected by gasket type sealing means without adversely effecting performance or efficiency of the compressor.
Still another object of the present invention is to provide a compressor system in which the clearance between the compressor rotor and the front cover of the compressor is not affected by the means used to seal leakage from the compressor to the atmosphere through the interface between the covers and the cylindrical section of the compressor housing.
A further object of the present invention is to provide a compressor assembly which does not require a separate line from the outlet of the compressor to the tank which receives the compressor discharge.
Yet, a further object of the present invention is to provide a compressor assembly having a compact envelope in which the tank which receives the discharge of the compressor also acts as an oil sump for the lubrication system of the compressor.
Still a further object of the present invention is to provide a compressor assembly in which the tank which receives the discharge of the compressor contains means to separate oil from the discharge of the compressor and acts as a sump for the lubrication system of the compressor.